The present invention relates generally to semiconductor fabrication and more specifically to processes of reflowing bumps.
Current bump reflow methods requires many machines such as flux coaters, reflow furnaces flux cleaners to do bump flux reflow. A flux chemical is required which is a pollution source. The reflowed bump height is low with a large diameter.
U.S. Pat. No. 6,179,200 B1 to Kung et al. describes a solder bump process.
U.S. Pat. No. 6,121,062 to Karasawa et al. describes another molder bump process.
U.S. Pat. No. 6,114,187 to Hayes describes a solder reflow process.
U.S. Pat. No. 5,125,560 to Degani et al. describes a solder reflow process using a flux.
Accordingly, it is an object of one or more embodiments of the present invention to provide an improved method of reflowing bumps.
Other objects will appear hereinafter.
It has now been discovered that the above and other objects of the present invention may be accomplished in the following manner. Specifically, a wafer is provided. A series of spaced initial bumps is formed upon the wafer. The initial bumps having exposed side walls and top surfaces and organic residue over the initial bump side walls and/or the initial bump top surfaces. The organic residue is simultaneously removed from the initial bump side walls and top surfaces with the forming a surface oxide layer over the initial bump side walls and top surfaces. The surface oxide layer is stripped from the initial bump top surfaces and an upper portion of the initial bump side walls to form partially exposed bumps. The partially exposed bumps are heat treated to melt the partially exposed bumps to form the reflowed bumps.